Q.1

Which of the following decreases during evaporative cooling process with recirculated water supply ?

  • Wet bulb temperature
  • Relative humidity
  • Partial pressure of vapour
  • None of these
Q.2

Which of the following provides maximum contact surface for a liquid-vapour system?

  • Packed tower
  • Bubble-cap plate column
  • Seive-plate column
  • Wetted wall column
Q.3

In a single stage extraction process,kg of pure solvent S (containing no solute A) is mixed withkg of feed F containing A at a mass fraction xf = 0.The mixture splits into an extract phase E and a raf-finate phase R containing A at xB = 0.5 and xR = 0.respectively. The total mass of the extract phase is (in Kg)

  • 6.89
  • 8.89
  • 10
  • 8.25
Q.4

Danckwerts developed the __________ theory.

  • penetration
  • surface renewal
  • film
  • none of these
Q.5

Desulphurisation of petrol is done in a

  • Bollman extractor
  • rotating disc extractor
  • packed extraction column
  • plate type extraction column
Q.6

Calculation of mass transfer co-efficient is mostly/normally done using __________ theory.

  • surface renewal
  • film
  • penetration
  • none of these.
Q.7

Which of the following is the correct ternery diagram for liquid-liquid extraction system comprising of two pairs partly soluble (e.g., chlorobenzene-water-methyl ethyl ketone system) ?

  • None of these.
Q.8

For a single component absorber, the operating line is straight only when plotted in term of __________ units.

  • partial pressure
  • mole ratio
  • mole fraction
  • none of these
Q.9

Laboratory determination of the dif-fusivity of vapor is done by __________ method.

  • wetted wall column
  • Gilliland's
  • Winkel mann's
  • Wike's
Q.10

The minimum liquid rate to be used in an absorber corresponds to an operating line

  • of slope = 1
  • ofslope = 0.1
  • tangential to the equilibrium curve
  • none of these
Q.11

For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is

  • calculated
  • unknown
  • known
  • not required
Q.12

In stripping section of continuous distillation column, the

  • liquid is stripped of high boiler.
  • liquid is enriched with high boiler.
  • vapour is stripped of low boiler.
  • none of these.
Q.13

Penetration theory states that the mass transfer co-coefficient is equal to (where, De is diffusivity and 't' is time)

  • (De.t)1/2
  • (De/t)1/2
  • (4De/πt)1/2
  • (4De/t)
Q.14

Chemisorption compared to physical absorption has

  • lower adsorption rate.
  • lower capacity of the solvent for the solute gas.
  • increased utilisation of stagnant zones of the liquid phase.
  • none of these.
Q.15

The velocity, concentration and temperature boundary, for the boundary layer development on a flat plate during connective mass transfer will be same, if

  • NSc = 1
  • NSc = NPr = NLe
  • NPr = NLe
  • NSc = NLe
Q.16

Reboiler is considered as one theoretical plate, because

  • of the assumption that vapour and liquid leaving the reboiler are in equilibrium.
  • vapour is recycled to the column.
  • reboiler itself contains one plate.
  • none of these.
Q.17

Rate of adsorption increases as the

  • temperature increases.
  • temperature decreases.
  • pressure decreases.
  • size of adsorbent increases.
Q.18

Pick out the system with maximum boiling azeotrope at 1 atm.

  • acetone chloroform
  • ethyl alcohol-water
  • benzene-ethyl alcohol
  • none of these
Q.19

In the layout plan for a vacuum distillation unit, operating atmm Hg, supported by a barometric condenser, the appropriate place for the location of vacuum drum for collecting the distillate will be

  • at ground level.
  • 2 metres above the ground.
  • 5 metres above ground.
  • 10 metres above ground.
Q.20

Which of the following is used for the concentration of rubber latex ?

  • Agitated film evaporator
  • Long tube vertical evaporator
  • Short tube evaporator
  • Calendria
Q.21

In a binary system, separation is very efficient, when the relative volatility is

  • 1
  • > 1
  • < 1
  • 0.5
Q.22

Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for

  • constant molal overflow
  • total reflux
  • constant relative volatility
  • all (a), (b) and (c)
Q.23

The binary diffusivity in gases does not depend upon the

  • pressure
  • temperature
  • nature of the components
  • none of these
Q.24

Berl saddle made of carbon cannot be used for

  • alkalis
  • SO2
  • H2SO4
  • oxidising atmosphere
Q.25

1 kg of a saturated aqueous solution of a highly soluble component A at 60°C is cooled to 25°C. The solubility limits of A are (0.6 kgA/kg water) at 60°C and (0.2 kgA/kg water) at 25°C. The amount in kg of the crystals formed is

  • 0.4
  • 0.25
  • 0.2
  • 0.175
Q.26

Which of the following is used for the concentration of rubber latex ?

  • Agitated film evaporator
  • Long tube vertical evaporator
  • Short tube evaporator
  • Calendria
Q.27

The diffusivity (D) in a binary gas mixture is related to the temperature (T) as

  • D ∝ T
  • D ∝ T0.5
  • D ∝ T1.5
  • D ∝ T2
Q.28

Dryer widely used in a textile industry is __________ dryer.

  • festoon
  • cylinder
  • conveyor
  • tunnel
Q.29

Heat load in a cooling tower

  • means the amount of heat thrown away (KCal/hr.) by the cooling tower.
  • is equal to the number of kg, of water circulated times the cooling range.
  • both (a) & (b).
  • neither (a) nor (b).
Q.30

__________ is used as an 'entrainer' for the separation of acetic acid-water mixture by distillation.

  • Furfural
  • Benzol
  • Butyl acetate
  • Hexane
Q.31

For which of the following unit operations, Lewis number is of significance ?

  • Adsorption
  • Binary distillation
  • Gas absorption
  • Humidification
Q.32

Tray spacing in a distillation column of dia 10-ft. used in petroleum refinery may be around __________ inches.

  • 5
  • 30
  • 60
  • 100
Q.33

Solvent used in extractive distillation

  • changes the relative volatility of the original components.
  • should be of high volatility.
  • should form azeotropes with the original components.
  • all (a), (b) and (c)
Q.34

Air at a particular humidity is heated in a furnace. The new dew point

  • decreases
  • increases
  • depends on the extent of heating
  • remain unchanged
Q.35

Smoke is an example of

  • solid dispersed in liquid
  • solid dispersed in gas
  • liquid dispersed in gas
  • gas dispersed in liquid
Q.36

In case of absorption with exothermic reaction, for fluids having

  • Pr = Sc; percentage change in heat and mass transfer flux will be the same for a given change in the degree of turbulence.
  • Pr = Sc = 1; total mass, momentum and thermal diffusivity will be the same.
  • both (a) and (b)
  • Pr = Sc ; there won't be any change in heat and mass transfer flux with changes in degree of turbulence.
Q.37

Rotary dryers cannot handle __________ materials.

  • free flowing
  • dry
  • sticky
  • grannular
Q.38

Relative volatility does not change appreciably with the change in

  • temperature
  • vapour pressure of either component
  • total pressure
  • none of these
Q.39

The overall mass transfer co-efficient for the absorption of SO2 in air with dilute NaOH solution can be increased substantially by

  • increasing the gas film co-efficient.
  • increasing the liquid film co-efficient.
  • increasing the total pressure.
  • decreasing the total pressure.
Q.40

The temperature to which a vapour gas mixture must be cooled (at varying humidity) to become saturated is called the __________ temperature.

  • dew point
  • wet bulb
  • dry bulb
  • none of these
Q.41

If a1 and a2 are the relative volatilities when the pressure in the distillation column is 1 and 2 atm respectively. Pick out the correct statement.

  • a1 = a2
  • a1 = 2a2
  • a1 = 0.5 a2
  • none of these
Q.42

In a packed tower, the value of HETP equals HTUOG, when the equilibrium and the operating lines are (where, HETP = height equivalant to a theoretical plate HTUOG = overall gas phase height of a transfer unit)

  • straight
  • parallel
  • both (a) & (b)
  • neither (a) nor (b)
Q.43

Which of the following adsorbant is used in the refinning of sugar ?

  • Bone charcoal
  • Wood charcoal
  • Silica gel
  • Activated clay
Q.44

Detergent solution is dried to a powder in a

  • spray dryer
  • spouted bed dryer
  • tunnel dryer
  • pan open to atmosphere
Q.45

Which of the following mixtures does not form an azeotrope at atmosheric pressure?

  • Water-alcohol
  • Methyl alcohol-acetone
  • Butyl acetate-water
  • None of these
Q.46

Pick out the correct statement.

  • Diffusivity decreases with increase in temperature.
  • Diffusivity increases with increase in molecular weight.
  • Diffusivity increases with the size of the individual molecule.
  • none of these.
Q.47

Boiling point diagram is not affected by the ambient

  • pressure
  • humidity
  • temperature
  • both (b) and (c)
Q.48

The dew point of a saturated gas phase equals the __________ temperature.

  • gas
  • room
  • wet bulb
  • none of these
Q.49

Flooding results in

  • high tray efficiency
  • low tray efficiency
  • high gas velocity
  • good contact between the fluids
Q.50

Entrainer used in azeotropic distillation should

  • form a low boiling azeotrope with one of the constituents of the mixture.
  • form a new azeotrope of low relative volatility with one of the constituents of the mixture.
  • have high latent heat of vaporisation.
  • have high viscosity to provide high tray efficiency.
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